Abstract. In this paper, different representations of WiFi access point signal information are tested on a hierarchical indoors localization system to identify the one that yields the least amount of localization error. Four representations were considered: Received Signal Strength (RSS) in dBm, RSS in mW , Visibility and both RSS in dBm and Visibility. The localization system was tested in two different real world environments and encouraging results were obtained for the combination of RSS in dBm and Visibility. The results point to increased accuracy in localization, especially in environments where signal is greatly distorted by the multipath effect.